System for the thermal preparation of reclaimed road material containing pahs or oil sludge

ABSTRACT

A system for the thermal preparation of reclaimed road material containing PAHs, or of oil sludge having a loading station for pre-comminuted reclaimed road material or oil sludge, a rotary kiln in which the reclaimed road material or the oil sludge is burned, while oxidation air is fed in, a dust separator to which the flue gases produced in the rotary kiln are fed, an after-burner to which the flue gases leaving the dust separator are fed, and a filter to which the flue gases arising in the after-burning means are fed. These components are divided into a plurality of modules, each of which includes a weight and dimension such that each may individually be transported using conventional road transport means, in particular low loaders or heavy goods vehicles.

RELATED APPLICATIONS

This application claims the filing benefit of German Patent Application No. 10 2012 016 882.9 filed Aug. 24, 2012, the contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a system for the thermal preparation of reclaimed road material containing PAHs, or of oil sludge, having

-   -   a) a loading station for pre-comminuted reclaimed road material         or oil sludge;     -   b) a rotary kiln in which the reclaimed road material or the oil         sludge is burned, while oxidation air is fed in;     -   c) a dust separator to which the flue gases produced in the         rotary kiln are fed;     -   d) an after-burning means to which the flue gases leaving the         dust separator are fed;     -   e) a filtering means to which the flue gases arising in the         after-burning means are fed.

BACKGROUND OF THE INVENTION

Relatively old roads were frequently built using a road surface in which pitch (coal tar) was used as a binder. Since pitch comprises a high proportion of PAHs (polycyclic aromatic hydrocarbons, lead substance: benzo[a]pyrene), which are harmful to the environment, the use of such reclaimed road material containing pitch is no longer permitted today. For this reason, the direct re-use in an asphalt mixing plant of reclaimed road material containing pitch which is prepared only mechanically is also ruled out. Rather, the binder containing pitch has to be removed from the grit in the reclaimed road material before the grit can be used to prepare fresh asphalt.

A system of the type mentioned at the outset which can be used to perform this required preparation is described in DE 10 2009 025 361 B4. This system is positioned at a fixed site in the vicinity of an asphalt mixing plant. Thus, in Germany, for example, in each case a central system has a federal state as its catchment area. For treatment, the reclaimed road material containing PAHs is transported from the entire catchment area to the fixed-site system. This results in a high wall for transport. A substructure is required for setting up the known system, which makes changes to the set-up and the ultimately necessary demolition of the system cost-intensive.

Oil sludge may in principle be disposed of using substantially identical methods. In these, similar problems in respect of their occurrence and in particular the location of the occurrence may arise to those described above for reclaimed road material. This is the case, for example, if there is a rupture in an oil pipeline.

An object of the present invention is to construct a system of the type mentioned at the outset such that the costs associated with its erection, operation and where appropriate dismantling are reduced.

SUMMARY OF THE INVENTION

This object may be achieved according to the invention in that the system components according to features a) to f) (discussed above) are divided among a plurality of modules, each of which have a weight and dimensions such that they may individually be transported using conventional road transport means, in particular low loaders or heavy goods vehicles.

According to embodiments of the invention, by comparison with the prior art the logistical structure is therefore reversed: whereas in the prior art the reclaimed road material or oil sludge is transported to the central preparation system at a fixed site, according to the invention the preparation system is taken to the location at which the educt occurs.

Surprisingly, it has also been found that the concept according to the invention of the mobile system has considerable potential for savings in the areas of the scope of transport and hence the costs of transport, by comparison with a fixed-site system. Set-up, changes to the set-up and dismantling of the system according to the invention at most require the use of a crane. The mobile system can rapidly be reconfigured, if this is required for example for reasons of space. It may also be operated on sites that have been allocated on a temporary basis and removed again at low cost once the processing task has been performed. Finally, the modules used according to the invention may be replaced variably and rapidly in the event of changes to the way the process is carried out or modernisation measures.

An advantageous embodiment of the invention additionally comprises a module in which the components required to supply the other modules, in particular a power unit, tanks for operating media such as water, gas, compressed air or fuel, are grouped together. Whereas it is not possible to build a fixed-site system at any conceivable location because a precondition is an underlying infrastructure of power supplies, with this preferred embodiment of the invention the mobile system can be operated at any desired construction site, since it is self-sufficient in terms of the supply of the appropriate energy carriers and media. As a result a high level of availability and safety is obtained for the companies operating the system.

It is further favourable if at least some of the modules are connected to one another by way of pipes or hoses that are of variable shape. This makes it easier to reposition the modules if this is required for example when moving on, or when changing construction site for reasons of space.

It has further proved favourable to divide the system components according to features a) to f) among four modules. In this way, with an average capacity of the system the required transportability of the individual modules is generally achieved.

To protect the filters, advantageously a flue gas cooler is arranged between the after-burning means and the filtering means.

It is to be understood that the aspects and objects of the present invention described above may be combinable and that other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing, for the case of preparing reclaimed road material. The thermal preparation of oil sludge is in principle performed in the same way. In the drawings:

FIG. 1 shows, schematically and in perspective, a first exemplary embodiment of a mobile system for the thermal treatment of reclaimed road material containing PAHs; and

FIG. 2 shows, in a similar view to that of FIG. 1, a second exemplary embodiment of a system of this kind

DETAILED DESCRIPTION OF THE PRESENT INVENTION

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more embodiments with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated.

Reference is first made to FIG. 1. The system which is illustrated here and which is overall designated by reference numeral 1 is intended for mobile use at different construction sites, to which it may be transported by road using low loaders. The system 1 comprises all the essential components intended to perform the method described in DE 10 2009 025 361 B4 mentioned above. Because of the mode of operation of the installed system, reference is made to this printed specification unless stated otherwise. These components are divided among four modules 2, 3, 4, 5 which are carried on trailers 6, 7, 8, 9. The trailers 6, 7, 8, 9 with the components set up on them may be connected to a tractor in known manner for transport.

The number of modules 2, 3, 4, 5 depends on the size of the system; in general, four modules 2, 3, 4, 5 are appropriate, as illustrated. For systems having a smaller or larger capacity, it is also possible to use fewer or more modules.

Set up on the first module 2 is a filling container 10 to which material containing PAHs, illustrated schematically in FIG. 1 and provided with reference numeral 11, is fed automatically or manually. The filling container 10 represents a loading station, in the terminology of the claims. The material containing PAHs passes by way of a line 12 to a rotary kiln 13, where it undergoes thermal processing in known manner. The thermally treated and now PAH-free material (inert material bearing reference numeral 15) is ejected by way of a further line 14 at the end of the rotary kiln 13 and transported away for re-use.

The trailer 7 of the second module 3 carries a cyclone 16 to which the flue gases from the rotary kiln 13 of the first module 2 are fed by way of a flexible pipe or hose connection 17. The cyclone 16 is illustrated in its operational position in FIG. 1, in which it is of not inconsiderable height. For transport, it may be turned down into an approximately horizontal position about an axle 18. The remaining solids are removed from the flue gases in the cyclone 16, and the flue gases are then fed by way of a pipeline 19 to an after-burning means 20 in which any undesirable organic constituents which are still present are burned. If necessary, the after-burning means 20 may also be turned down, similarly to the cyclone 16, if this is necessary for transport. The corresponding axle is not illustrated in FIG. 1.

Set up on the trailer 8 of the third module 4 is a flue gas cooler 21 to which the hot flue gases leaving the after-burning means 20 of the second module 3 are fed by way of a flexible pipe or hose connection 22. In the flue gas cooler 21, the flue gases are cooled to a suitable low temperature by water which is sprayed in or with the aid of a heat exchanger, and they are then fed by way of a line 23 to a filtering means, in the exemplary embodiment illustrated a fabric filter 24. The latter is also on the trailer 8 of the third module 4. Finally, a suction fan 25 on the trailer 8 draws the cooled flue gases out of the fabric filter 24 and puts all the system components which are upstream, from the point of view of flow, under negative pressure. The flue gases which are drawn off by the suction fan 25 and which have at this point been cleaned in accordance with the provisions of the 17th BImSchV [Federal Immission Control Act] a (public-law ordinance in Germany) may be discharged to the ambient atmosphere by way of a chimney 26.

The third module 5 of the system 1, carried by its trailer 9, comprises all the components required to supply the components that take an active part in the process, which are on the three modules 2, 3, 4. This is particularly true of components that are required for power supply, for example a power unit 27, which is indispensable in particular on construction sites that are far away from the mains electricity supply. It goes without saying that a means of connection to the mains may additionally be provided. Further tanks 27, 28, 29, 30 comprise auxiliary media such as air, gas, water or indeed diesel fuel.

The system 1 described operates as follows:

When reclaimed road rubble containing PAHs occurs in relatively large quantities during road works, it is not taken to a fixed-site system, at a greater or lesser distance away, by heavy goods vehicle. Instead, the system 1 illustrated in FIG. 1 is brought to the construction site with the aid of four low loaders, each carrying a module 2, 3, 4, 5. For this, it goes without saying that the connections between the individual modules, in particular the flexible pipe or hose connections 17, 22 and the electrical connections, are first disconnected. The various modules 2, 3, 4, 5 are then positioned on site, wherein the arrangement is made largely according to the spatial conditions prevailing.

The system 1 is made ready for operation by making the various connections, in particular the flexible pipe or hose connections 17, 22 and the electrical connections. It is then possible to begin operation, in principle in the same way as that described in DE 10 2009 025 361 B4. There is, however, a difference in that the recovery of heat from the flue gases produced is dispensed with, and instead the flue gases are cooled, with the loss of the corresponding heat. This results purely from the fact that, at the construction site, there are not generally any consumers for this heat available on site.

However, as illustrated in the drawing by broken lines, it is possible to use the heat in the flue gases from the rotary kiln 13 and/or the after-burning means 20 to pre-heat the oxidation air. This may be done for example with the aid of the flue gas cooler 21, to which for this purpose fresh oxidation air is fed, wherein, after the heating which takes place on cooling of the flue gases, this oxidation air is fed to the rotary kiln 13 and/or the after-burning means 20.

If the construction site continues along a road which is to be repaired, the mobile system 1 can follow this construction site, with the result that the transport distances are always very short.

FIG. 2 illustrates a system for the thermal treatment of reclaimed road rubble containing PAHs, wherein the only difference is that it is not intended for exclusively road transport on low loaders but where appropriate also for transport by rail or ship or indeed other heavy goods vehicles. To this end, the trailers 6, 7, 8 are replaced by platforms 106, 107, 108 which are each on four legs and may where appropriate also be accommodated in containers. Otherwise, the system in FIG. 2 corresponds in its operation and construction to the individual modules and the connections between the latter to that in the system 1 in FIG. 1. For this reason, corresponding parts are designated in FIG. 2 by the same reference numeral plus 100. 

Claimed is:
 1. A system for the thermal preparation of reclaimed road material containing PAHs, or of oil sludge, comprising: a loading station for pre-comminuted reclaimed road material or oil sludge; a rotary kiln in which the reclaimed road material or the oil sludge is burned while oxidation air is fed in; a dust separator into which flue gases produced in the rotary kiln are fed; an after-burner to which the flue gases leaving the dust separator are fed; a filter to which the flue gases arising in the after-burner are fed, wherein the loading station, the rotary kiln, the dust separator, the after-burner, and the filter are divided into a plurality of modules, each of which has a weight and dimensions such that each is capable of individually being transported using conventional road transport means.
 2. The system according to claim 1, further comprising: a module in which components required to supply the modules from the plurality of modules with operating media are grouped together.
 3. The system according to claim 1, wherein at least two of the modules from the plurality of modules are connected to one another by way of a pipe or a hose having a variable shape.
 4. The system according to claim 1, wherein the loading station, the rotary kiln, the dust separator, the after-burner, and the filter are divided into four modules.
 5. The system according to claim 1, further comprising: a flue gas cooler arranged between the after-burner and the filter.
 6. The system according to claim 1, wherein a heat in the flue gases from the rotary kiln and/or the after-burner is used, at least in part, to pre-heat the oxidation air, which is fed to the rotary kiln and/or the after-burner. 